Conventional transmitters and receivers often communicate over transmission lines. For example, a transmitter may communicate with a receiver over an Ethernet cable. In conventional communication systems, a signal transmitted from a transmitter to a receiver over a transmission line is partially reflected back to the transmitter. To help minimize reflection, the impedance of the transmitter typically needs to match the characteristic impedance of the transmission line.
Several techniques have been developed to match the impedance of a transmitter to the characteristic impedance of a transmission line. However, these approaches typically suffer from a number of problems. For example, some techniques suffer from current or voltage loss and are sensitive to process variations during the manufacturing process. Also, some techniques require more complex circuitry that is external to the transmitting circuitry, which increases the size and complexity of the transmitter.